Combination vacuum chamber and high voltage terminal



Oct. 13, 1964 D. A. SWICK 3,153,115

COMBINATION VACUUM CHAMBER AND HIGH VOLTAGE TERMINAL Original Filed March 28. 1961 35 55 as 32 u 58- '54 62- 52 45 INVENTOR HIGH 46 47 D AV I D A. SW l c K VOLTAGE SOURCE Q ATTORNEY United States Patent The invention described herein may be manufactured and used by or for the Government of theUnited States of America for governmental purposes without the payment of any royalties thereon or therefor.

The presentinvention is a continuation of application Serial No. 98,989, filed March 28, 1961, now abandoned, and relates to means for conducting electrical voltages into a chamber and more particularly to an electrical terminal adapted to conduct high Voltagesinto a vacuum chamber. v

Her'ctofore terminals have been constructed which consist of glass-to-metal seals through which, a conductor is passed to conduct an electrical voltage through the walls of a chamber. Such terminals have their drawbacks wherein the glass-tometal seals break easily, and for use with a vacuum system, the glass-to-metal seals leak or outgas such that a vacuum cannot be eiiiciently maintained in a chamber into which the electrical voltage is directed. In order to prevent a high voltage breakdown and in order to protect personnel from contact with high voltage in systems wherein ahigh voltage is directed into a chamber in which the walls are grounded, it is required that a seal be maintained betweenthe conductor at high voltage and the groundedwall.

it is therefore an object of the present invention toprovide an electrical terminal suitable for conducting high I voltages into a vacuum system in which the walls of the vacuum system are grounded. 1

Another object is to provide an electrical terminal which is nonbreakable and will maintain a good, vacuum seal.

Another object is to provide an electrical terminal which will assure adequate presure in the vacuum system into which an electrical voltage is conducted.

Yet another object is to provide an electrical terminal which is simple in structure, relatively small in size,

relatively inexpensive, easy toassembleyand yet is suiliciently rugged to withstand high voltages.

Other and more specific objects of this invention will become apparent upon a more careful consideration of the following, detailed description when taken together with the accompanying drawing in which the drawing is a cross section of the devicewhich illustrates the features of the invention.

The electrical terminal comprises a polytetrafiuoroethylene insulator (which is known and sold by its trademarkterm, Teflon) which fits Within a brass or other metallic conductor in which the brass conductor is secured to the wall of avacuum chamber. The Teflon insulator is made such that'an electrical terminal is secured within it. An electrical conductor is passed vacuum chamber through the walls thereof. A vacuurn' is maintained in the vacuum chamberthrough use of gaskets wherein the gaskets have a minimum exposure to any through cracks or openings into the vacuum system. Electrical contact is made with the terminal through a brass'or other metal- 3,.l53,ll5 Patented Get. 13, 1964 ice , Now referring to the drawing, there is shown a cross sectional view of a device which comprises an elongated metal tubular cylinder 11 which may be made of brass j screw threaded holes 17 therein which receive suitable screwthreaded screws such as 18. The tubularmember ll. provides a conductive sleeve which receives a tubular Tcllon insulator 21 or an insulator made. of a similar material which has anelongated end 22 of the same length as the sleeve and fits therein with a snug fit. The insulator is provided with a radial flange 23 which extends along the flange 12 of the sleeve a distance slightly less than the distance to the holes 14 which pass through the flange 12 and has an end 24 which extends from the fiangeinto the vacuum chamber through an aperture in the chamber Wall 16. The outsidediameter oi the insulator is equal to the inner diameter of the Teflon sleeve and the inner diameter of the insulator is slightly greater than the supplycable used. The inner surface of the insulator opposite to the flange 12 is provided with a ridge or a radial inwardly extending flange 25 which extends inwardly from the wall surface in a plane with flange 23 and includes apassage 26 from the end 22 to the end 2 The ridge 25 is provided with holes 27 passing therethrough, the purpose of which will be explained later. A brass or any other suitable metallic conductor 36 having linear portions of different radii is inserted through the end 2 5 of the insulator with the central portion 31 fitting snugly into pasage 26 with an end 32 of smaller diameter that extends into the area bounded by the end portion 22 of the insulator. The conductor is also provided with an enlarged portion 33 which extends along the vacuum side of the ridge 25 and has a diameter slightly less than the inner diameter of the insulator end The end 33 of the conductor has blind threaded holes 34 therein wh'ch receive the end of bolts 35 which pass through the holes 27 in the ridge 25. The bolts 35 pass through a pressure ring 36 on the air side of the ridge 25 and a gasket 37 is secured between the pressure ring 36 and the ridge 25 which closes the air space between the central portion 31 of the conductor Fill and the passage 25: between the end sectionsZd and-22 of the insulator. The screws 35 pass through the pressure ring 3d and the gasket 37 and the ridge I15 and screw into the threaded holes 34 of end 33 of the conductor 36; whereby the screws are tightened against the gasket to seal the space between ridge 25 and the section 31 of the conductor 3%. Such an assembly provides a vacuum seal between theridge 25 and the largest portion 33 of the conductor i would permit a leak. The portion 33 of the conductor ductor 39 thereto.

30 has a blind hole therein within which a wire connector it? can besecurcd to electrically connect a con- The electrical conductor then con- .nects at the other end to the element to which the high he plate held in place by a compression spring which is I connected through a fuse wire and a surge resistor toan electrical conductor cable which is shielded'about the outside; The shield about the outside of the cable is connected to the brass conductor to complete the circuit with the grounded wall of the vaccum chamber.

voltage'is to be supplied. The connector 38 has channels in it to permit rapid vacuum pumping o f'any gas trapped between it and conductor 36 e V The opening in the vacuum wall to which the vacuum seal'terminal is connected is made in a step configuration to receive the insulator from the air side of the vacuum wall. The opening on the vacuum side is of a diameter only large enough to receive the end 24 of the insulator. The portion of the opening inthe vacuum wall that is toward the air side is of a diameter larger than that porarea;

tion toward the vacuum side and is sufliciently large to receive the flange 23 of the insulator. A gasket 41 is placed between the flange 12 of the sleeve 11 and the wall surface 16 of the vacuum chamber such that the gasket covers a portion of the surface of flange 23 and the wall surface of the vacuum chamber 16 to cover the craclr joint between the two members 16 and Z5. Bolts 15 are passed through the flange 12 and screwed into the vacuum wall surface 16 and tightened such that the gasket 41 will compress and insure a vacuum seal between the insulating member 21 and the vacuum wall 16.

The cylindrical outer conductive sleeve 11 is provided with a plate 42 at the outer end which is secured thereto by screws 18 which screw into the flange 13 of the cylindrical sleeve 11. The plate 4?. is provided with an axially extending opening therein with a wall surface perpendicular to the plate surface. The wall surface 4-3 is provided with screw thread openings which receive screws 44, the purpose of which will be explained later.

A high voltage is transmitted from a voltage source 40 to the vacuum seal conductor by a cable which includes a grounded shield 45, and a center wire 46 which are separated by an insulation material 47. The grounded shield 45 is stripped back a short distance from the end of the cable and the stripped end of the cable including the insulation and the Wire is inserted into the end 22 of the insulator 21 through the axial opening of the plate 42. The grounded shield is connected to the wall 43 of the plate 42 by screws 44, this connection provides a ground contact with the vacuum wall 16 through the metal cylindrical sleeve 11 which is connected to the wall surface by screws 15. The high voltage is transmitted from the wire through a surge resistor 48 which is connected to a fuse wire 51. The fuse 51 is connected to a brass plate 52 which is held in position by a Teflon holder 53. A spring 54 is soldered to the plate 52 and to another plate 55 which is forced against the end 32 of the brass conductor 39. Therefore, electrical voltage passes from the wire 46 to the conductor 3t? through the surge resistor 48, the fuse 51 and the spring brass plate arrangement 52, d and 55. The Teflon holder 53 is made in two pieces 57 and 58. The piece 57 has an outside diameter equal to the diameter of the end of the cable which is inserted into the end 22 of the Teflon insulator 21. The portion 57 has a partition therein which acts as a means for holding one end of the resistor 48. The end furthest removed from the cable has a portion 61 which has an inner diameter greater than the inner diameter of the other portion. Such an arrangement affords a seat for the brass plate 52 which is held in place by the upper portion 58 of the Teflon holder. The upper portion has an outer diameter which is equal to the inner diameter of the insulator 21 and has a portion 52 connected therewith which is inserted into the end portion 61 of the piece 5'7 of the insulator holder. The brass plate 55 is made of such a diameter that it will slide within the inner diameter of the part 58 of the holder 53. The spring 5 forcing against the secured plate 52 and the movable plate 55 insures a good electrical contact with the end 32 of the conductor Stl.

In carrying out the assembly of the device the vacuum sealed conductor 30 is secured in place by screws 35. Insulator 21 is fitted with the end 22 into the sleeve 11 and secured to the vacuum wall 16 by screws 15 with suitable gaskets between the surfaces. The grounded shield of the cable is removed for a short distance along the end of the wire and the cap 42 is slipped over the cable and secured thereto with the screws 44. The resistor, fuse, brass plates and spring arrangement is fitted into the Teflon holder 53 and the outer end of the resistor is connected to the wire 46 of the cable. The Teflon holder arrangement is passed into the end 22 of the insulator along with the stripped end of the cable and then the cap 42 is secured to the sleeve 11 by bolts 13. Since the cable is held in place in the cap 42 by bolts 44,

the spring will hold the brass plate 55 in contact with the end 32 of the vacuum sealed conductor 30.

Such an arrangement affords a vacuum tight electrical terminal suitable for conducting high voltages into a vacuum system through the grounded walls of the vacuum system. Such an arrangement provides a minimum surface subject to outgassing and is made of a material which is not subject to breakage or electrical breakdown.

The high voltage terminal has been described as useful for a grounded vacuum chamber wall wherein the sleeve about the insulator completes a circuit to ground. Such a high voltage terminal can be used in a vacuum tube or any other structure wherein oppositely disposed terminals can be secured in an insulator and a filament or conductor connected between the two terminals without a ground connection to the wall of the tube. In such an arrangement the insulator could be connected to the tube structure by a flange which has a shoulder that extends over the flange of the insulator. Thus the insulator would be secured in position by pressure applied to the insulator flange by the shoulder on the securing flange. In this manner the terminal would be insulated from the tube wall and the circuit could be completed by a connection with each terminal.

Obviously many modifications and variations of the present invention are possible in the light of the above teachings. It is therefore to be understood that within the scope of the appended claims the invention may be practiced otherwise than as specifically described.

What is claimed is:

1. In combination, a vacuum chamber and a high voltage electrical terminal that makes an electrical connection between the vacuum side and the non-evacuated side of said vacuum chamber to transmit a high voltage from a power source into said vacuum chamber whose walls are at ground potential which comprises:

an aperture in one wall of said vacuum chamber,

(a) an elongated tubular insulator secured in said aperture in said wall of said vacuum chamber,

(b) said tubular insulator including one end that extends beyond said wall into said vacuum chamber and an end which extends outwardly from said non-evacuated side of said chamber,

(c) an integral flange on the outer perimeter of said tubular insulator that extends radially along the wall of said vacuum chamber a short distance surrounding said aperture therein,

(d) an integral flange on the inner periphery of said insulator,

(e) an aperture in said inner flange forming an opening between the ends of said insulator,

(1) an electrical conductive sleeve,

(g) said electrically conductive sleeve surrounding said tubular insulator portion that extends outwardly from said chamber,

(h) a radially extending flange on the periphery of said conductive sleeve at the end thereof toward said vacuum chamber extending along said integral flange on the perimeter of said tubular insulator,

(i) said flange on said sleeve extending along said integral flange on the outer perimeter of said insulator and said vacuum chamber wall a greater distance than said flange on the outer periphery of said tubular insulator,

(j) means securing said conductive sleeve flange to said chamber wall thereby forcing said conductive sleeve flange against said integral flange on the outer perimter of said tubular insulator to secure said insulator flange against the wall of said vacuum chamber,

(k) said conductive sleeve forming a ground conductor as well as providing protection for said insulator sleeve,

(1) an electrical terminal conductor,

(In) said electrical terminal conductor having a portion thereof extending along the vacuum side surface of said inner flange on the insulator and a portion extending through said aperture and into the area confined by said insulator on the non-evacuated side of said chamber, and

(n) means for securing said electrical terminal conductor in a vacuum tight seal to said inner flange on said insulator element.

2 In combination, a vacuum chamber and a high voltage electrical terminal that makes an electrical connection between the vacuum side and the non-evacuated side of said vacuum chamber to transmit a high voltage from a power source into said vacuum chamber whose walls are at ground potential, which comprises:

, an aperture in one Wall of said vacuum chamber,

I! (a) an elongated tubular insulator secured in said aperture in said Wall of said vacuum chamber,

(b) said tubular insulator including one end that extends through said aperture in said vacuum chamber beyond said wall into said vacuum chamber and an end which extends outwardly from said non-evacuated side of said chamber,

(0) an integral flange on the outer perimeter of said tubular insulator extending radially along said wall surface for a short distance surrounding said aperture therein,

((8) an integral flange on the inner periphery of said insulator in a plane with said integral flange on the outer perimeter of said insulator,

(e) an axial aperture within said integral flange on the inner periphery of said insulator,

(f) an electrical conductive sleeve,

(g) said electrical conductive sleeve surrounding said tubular insulator portion extending outwardly from said chamber,

(h) a radially extending flange on the periphery of said conductive sleeve at the end thereof ada iacent said vacuum chamber extending along said integral flange on the perimeter of said tubular insulator,

(i) said flange on said sleeve extending along said integral flange on the outer perimeter of said insulator and the Wall of said vacuum chamber a greater distance than said flange on the outer periphery of said tubular insulator, I

(j) means securing said conductive sleeve flange to said chamber Wall thereby forcing said conductive sleeve flange against said integral ilange on the outer perimeter of said insulator to secure said insulator flange against thewali of said vacuum chamber,

(k) said conductive sleeve forming a ground conductor as well as providing protection for the insulator sleeve,

(I) an electrical terminal conductor,

(in) said electrical terminal conductor having a portion thereof extending along the vacuum side surface of said inner flange on the insulator and a portion extending through said aperture and into the area confined by said insulator on the non-evacuated side of said chamber, and

(a) means for securing said electrical terminal conductor in a vacuum tight seal to said inner flange on said insulator element.

References in the file of this patent UNITED STATES PATENTS 1,264,674 Moller Apr. 30, 1918 2,374,560 Nelson Apr. 24, 1945 2,453,397 Yonkers Nov. 9, 1948 FOREIGN PATENTS 565,677 Canada Nov. 4, 1958 813,464 Great Britain May 13, 1959 1,248,393 France Oct. 31, 1960 

1. IN COMBINATION, A VACUUM CHAMBER AND A HIGH VOLTAGE ELECTRICAL TERMINAL THAT MAKES AN ELECTRICAL CONNECTION BETWEEN THE VACUUM SIDE AND THE NON-EVACUATED SIDE OF SAID VACUUM CHAMBER TO TRANSMIT A HIGH VOLTAGE FROM A POWER SOURCE INTO SAID VACUUM CHAMBER WHOSE WALLS ARE AT GROUND POTENTIAL WHICH COMPRISES: AN APERTURE IN ONE WALL OF SAID VACUUM CHAMBER, (A) AN ELONGATED TUBULAR INSULATOR SECURED IN SAID APERTURE IN SAID WALL OF SAID VACUUM CHAMBER, (B) SAID TUBULAR INSULATOR INCLUDING ONE END THAT EXTENDS BEYOND SAID WALL INTO SAID VACUUM CHAMBER AND AN END WHICH EXTENDS OUTWARDLY FROM SAID NON-EVACUATED SIDE OF SAID CHAMBER, (C) AN INTEGRAL FLANGE ON THE OUTER PERIMETER OF SAID TUBULAR INSULATOR THAT EXTENDS RADIALLY ALONG THE WALL OF SAID VACUUM CHAMBER A SHORT DISTANCE SURROUNDING SAID APERTURE THEREIN, (D) AN INTEGRAL FLANGE ON THE INNER PERIPHERY OF SAID INSULATOR, (E) AN APERTURE IN SAID INNER FLANGE FORMING AN OPENING BETWEEN THE ENDS OF SAID INSULATOR, (F) AN ELECTRICAL CONDUCTIVE SLEEVE, (G) SAID ELECTRICALLY CONDUCTIVE SLEEVE SURROUNDING SAID TUBULAR INSULATOR PORTION THAT EXTENDS OUTWARDLY FROM SAID CHAMBER, (H) A RADIALLY EXTENDING FLANGE ON THE PERIPHERY OF SAID CONDUCTIVE SLEEVE AT THE END THEREOF TOWARD SAID VACUUM CHAMBER EXTENDING ALONG SAID INTEGRAL FLANGE ON THE PERIMETER OF SAID TUBULAR INSULATOR, (I) SAID FLANGE ON SAID SLEEVE EXTENDING ALONG SAID INTEGRAL FLANGE ON THE OUTER PERIMETER OF SAID INSULATOR AND SAID VACUUM CHAMBER WALL A GREATER DISTANCE THAN SAID FLANGE ON THE OUTER PERIPHERY OF SAID TUBULAR INSULATOR, (J) MEANS SECURING SAID CONDUCTIVE SLEEVE FLANGE TO SAID CHAMBER WALL THEREBY FORCING SAID CONDUCTIVE SLEEVE FLANGE AGAINST SAID INTEGRAL FLANGE ON THE OUTER PERIMETER OF SAID TUBULAR INSULATOR TO SECURE SAID INSULATOR FLANGE AGAINST THE WALL OF SAID VACUUM CHAMBER, (K) SAID CONDUCTIVE SLEEVE FORMING A GROUND CONDUCTOR AS WELL AS PROVIDING PROTECTION FOR SAID INSULATOR SLEEVE, (L) AN ELECTRICAL TERMINAL CONDUCTOR, (M) SAID ELECTRICAL TERMINAL CONDUCTOR HAVING A PORTION THEREOF EXTENDING ALONG THE VACUUM SIDE SURFACE OF SAID INNER FLANGE ON THE INSULATOR AND A PORTION EXTENDING THROUGH SAID APERTURE AND INTO THE AREA CONFINED BY SAID INSULATOR ON THE NON-EVACUATED SIDE OF SAID CHAMBER, AND (N) MEANS FOR SECURING SAID ELECTRICAL TERMINAL CONDUCTOR IN A VACUUM TIGHT SEAL TO SAID INNER FLANGE ON SAID INSULATOR ELEMENT. 